First, choose your yarn. No fun fur or bouclé yarn, you want neat stitch definition for this project.
I’m using the long-discontinued Rowan “All seasons cotton”
You’ll also want to have enough of this yarn to make ALL the samples of the series (sot they can all be compared). I’d say have at least 200 m…
Choose a hook which works well with this yarn: crocheted fabric should be not too tight, not too loose. I’m using a 5 mm (H) Susan Bates hook

Step 1 – REGULAR DC = DC IN BOTH LOOPS

Let’s start our sampler with 6 rows of DC in both loops as a reference to compare the other stitches to.

Chain 22.
Turn and work a double crochet (dc) in 4th chain from hook. Then dc in each chain across. Turn work. You should have 20 sts (including initial ch3, which counts as 1st st. I know there are options for this, but let’s keep this for later)
We’re now going to insert the hook under BOTH loops of each stitch: when you look the top of the stitches, you see a “V” sitting on top of each dc. Both legs of the V = both loops.

You have now 6 rows of dc in both loops. Mark last row of dc in back loop with a stitch marker.

Step 2 – DC IN THE THIRD LOOP

After working in the front or back loop in Episode 1, let’s discover yet a new place to insert our hook into: the third loop !
If you look at the front/ right side of your work, you’ll see a little horizontal bar sitting at top of each stitch: it’s the 3rd loop.

Soon enough you’ll see clear lines of “V”s appearing on the wrong side while working a row. Those will produce lines separating each set of 2 rows, a little like when working in the front loop, but more visible.

You have now 6 rows of dc in 3rd loop. Mark last row of dc in 3rd loop with a stitch marker.

Step 3 – FRONT POST DC

Now this one is a bit more common, so you might already suspect that you’ll be crocheting AROUND the post (=vertical part of each dc) of each dc.

For the front post dc, insert your hook around the post while working on the front /right side of the work: insert hook from front to back in between 2 posts, then come back after post of the dc from back to front to RS of fabric again.